Flat Wire Wave Winding
With flat wire wave winding technology from Schaeffler ELMOTEC STATOMAT, e-drives can be realized considerably lighter, with significantly lower material consumption and lower costs.
With the process-reliable realization of winding technology, ELMOTEC STATOMAT has established a manufacturing technology that significantly optimizes the electric motor. The advantages are even potentiated if the design of a complete drive unit is adapted accordingly. The flat wire wave winding (continuous hairpin) uses a flat wire like the currently common hairpin process, which fills the available space in the slot with copper to a maximum.
However, while the hairpin process requires hundreds of copper wire ends to be welded to the respective counterpart on one side of the stator, the ELMOTEC STATOMAT winding does not require any welding points – a continuous copper wire is wound as a “mat” and then pressed into the slots.
ELMOTEC STATOMAT has succeeded in making this complex process reliable together with Schaeffler’s special machinerydepartment. The technology is ready for the series production.
There are two main advantages in the engine itself: By eliminating welding, thinner wires can be used. And the stator is shorter because eight to ten millimeters of additional wire and thus installation space are required for the welded connections. More significant in terms of the overall system, however, are the increased design degrees of freedom, which enable higher numbers of slots and wires and thus allow a significant reduction in high-frequency losses and improved heat exchange.
Particularly with high-speed designs, this advantage ensures higher efficiencies. The gear unit is given an adjusted transmission ratio in line with the speed increase, so that the same speed and torque values are again available at the wheel. However, the size of the gear unit remains comparable.
In concrete terms, for example, a comparison of two E-axles with a hairpin-wound motor and one with a flat wire wave winding shows clear results: When the speed is increased from 14,000 to 18,000 rpm, the wave-wound machine manages with almost one-third less magnetic mass, copper mass and total mass each. The overall length can be reduced by a quarter, which has a direct impact on the size, weight and cost of the e-axle system.
Not only in terms of e-drive design, but also in terms of production, the new technology offers significant advantages over the already established hairpin applications. Process reliability can be significantly increased through a significant reduction in the number of production steps required.
By winding a continuous mat around a so-called winding sword, separate stripping as well as pre-assembly of the individual hairpins is no longer necessary. The central technical advantage of the flat wire wave winding is that significantly fewer wire ends have to be processed after the winding has been assembled. The cutting, stripping, welding and final insulation of the “weld side” not only requires a high investment, but also poses significant risks with regard to the electrical insulation of the stator.
The development of a highly innovative process for bending the wire not only reduces the number of wire ends required for contacting on the connection side, but the wires to be contacted are located directly next to each other. This approach reduces the effort required for contacting and subsequent assembly of the busbars.
Another advantage of producing a continuous mat is that the number of wires used can be minimized. As a result, fewer tolerances have to be compensated for, which can cause errors in subsequent processes.
“With the complete automation of flat wire wave winding technology, we have made an important contribution to the next generation of highly efficient electric motors,” emphasizes Jochen Klee, Managing Director at Schaeffler ELMOTEC STATOMAT. “We are convinced that this technology represents one of the key manufacturing technologies for electromobility. We are thus optimally prepared for the future to realize the next generation of electric motors together with our customers and partners.”
Jochen Klee, Managing Director
Schaeffler ELMOTEC STATOMAT
In addition to "flat wire wave winding", discover other specializations in the field of e-mobility:
Whether electric axle, hybrid module, hybrid transmission or wheel hub drives, discover innovative winding technologies for your drive.